Seattle Land Use Code

Multi-family code passes 9-0

A triumph for the 'Seattle Way'--years of contentious hearings, studies, tweaks resolve into ultimately a unanimous decision.  There is a certain super-tanker inertia about the city process that eventually prevails but it does it take a quite a while to steer the ship of state toward higher goals. Big thanks to Councilmember Sally Clark, the DPD staff, and CORA supermen:  Brandon Nicholson, Bradley Khouri, and David Neiman.

New Multi-family code: vote on Monday?

L3-max-front-NE-2The new Multifamily Code is scheduled to come up for a vote before Council on Monday.  After years of process, hearings, and work shaping the outcomes, the new code will have some new attributes geared toward more flexibility in heights, parking, setbacks, and density.  It disincentivizes the '6 pack' townhomes everyone dislikes and gives out bonuses for green building, designs that hid parking and give a better streetscape.

For those of us who participated in the sausage-making legislative process over the years, it is great to see that it will finally come up for a vote.  If you want to see the vote, and who wouldn't, it will be at City Hall at 2pm Monday.


The Seattle channel recently interviewed myself and CAST clients Kate Lichtanstein and Ric Cochrane regarding the backyard cottage we are currently working on together. They included our project in a broader story that profiles an owner of a recently completed backyard cottage and gives a basic outline of the new Seattle backyard cottage ordinance.

Seattle Channel Video can be played in Flash Player 9 and up


Are you considering building a backyard cottage? We've put together a Seattle Backyard Cottage Quick Start Guide* to help homeowners better understand Seattle's citywide backyard cottage ordinance and the opportunities available to them.

The first step is to figure out whether or not your lot is large enough to qualify for a backyard cottage. The chart below outlines the minimum requirements for lot area and dimensions. lot_dimensions

Minimum Lot Size 4000 sq.ft.
Minimum Lot Width 25 feet
Minimum Lot Depth 70 feet

spacer The next step is to figure out what portion of your lot is buildable under the backyard cottage ordinance. Setbacks, yard requirements and maximum lot coverage all factor into whether or not a cottage is feasible. BUILDABLE-AREA

Setback from lot lines 5' unless adjacent to an alley in which case the setback is 0
Setback from other structures 5'
Maximum Lot CoverageSMC 23.44.010 Lots less than 5,000 sq. ft. - 1,000 sq. ft. + 15% of lot area
Lots 5,000 sq. ft. or more - 35% of lot area
Maximum Rear Yard Coverage 40% of the area required for the rear yard.
Maximum Front Yard Coverage Cottages not allowed in front yard.
Off Street Parking SMC 23.44.016 One space per dwelling unit required - some exceptions apply.
Entry Location May not be located on the side facing the nearest lot line unless that lot line abuts an alley or other public right of way.

spacer Once you've verified that your lot can accommodate a backyard cottage the next step is to take a look at the the floor area and height restrictions in order to determine if you can meet your objectives within those boundaries. GROSS-FLOOR-AREA-3

Gross Floor Area SMC 23.86.007 800' square feet max.Gross Sq. Ft. is measured from interior finished surface to interior finished surface. If you are planning a two story structure the floor area of each story counts toward the total.

spacer There are three factors that set the height limit for your cottage, the width of your lot, the type of roof you choose and the height of your home.

Lot width
< 30' 30'-35' 36'-40' 41'-50' 50' <
Max base height 12' 14' 15' 16 16
Max height with pitched roof 15' 21' 22' 22' 23'
Max height with shed or butterfly 15' 18' 19' 20' 20'
Max height above peak of existing home 15' 15' 15' 15' 15'


CAST Architecture tim@CASTarchitecture.comFeel free to email me with any questions you may have regarding Seattle's Citywide backyard cottage ordinance
Seattle Department of Planning and Development (DPD) Seattle Backyard Cottage OrdinanceThis is the definitive legal document covering Seattle Backyard Cottages.
DPD's Land Use Q&A ServiceAny ambiguities or clarifications unanswered by the ordinance document (above) can be addressed through the DPD's Land Use Q&A Service
DPD CAM 116B - Establishing a Backyard CottageThe DPD's client assistance memo (CAM) outlining the citywide backyard cottage ordinance. CAMs are guides intended to help people navigate the building permit processes in the city of Seattle.
A Guide to Building a Backyard Cottage in Southeast SeattleThis is an out of date but very useful guide put together by the DPD for Backyard Cottages in Southeast Seattle. The ordinance the guide was written for has changed (proceed with caution) but the value of the guide is still intact. It covers many of the issues you are likely to encounter and does a good job of mapping out design considerations you should be aware of.

*This guide is intended as an overview of the backyard cottage ordinance and does not include detailed conditions and restrictions that may affect individual properties. Please note that the guide was created in 2010 and that zoning codes may have changed since then. As such, it should only be used as a basic starting point for planning. If you would like to move forward with the design and permitting of a backyard cottage for your home we recommend careful scrutiny of the entire ordinance and the assistance of an architect or design professional.spacerDownload guide as a printable pdf Download guide as a printable pdf spacer

Demographics of a Seattle Backyard Cottage

demographicsWe've seen an unexpected level of interest in backyard cottages in the 2 months since the new ordinance has been in effect. Perhaps the most interesting thing about the projects is the diversity of needs for each one... We have a young couple with a small house on a large lot that would like an outbuilding with a workshop and guestroom. We have a couple planning to build and occupy a cottage in their backyard in order to open up their home for their children and grandchildren to live in. We have a third couple who have separated but are committed to raising their children together. They currently live in the same house and believe that adding a backyard cottage to the property will maintain the proximity they need to raise their children together while providing them the space they need as individuals.

In a bit of a surprise, we have yet to see anyone looking to build a cottage for the sole purpose of rental income. Although one of the guys here at the office has been running the numbers and is strongly considering building a cottage for rent in his backyard.


intro-image We've completed the first round of design on our CAST architecture case study backyard cottage.

Kate and Ric's cottage is intended to serve as an art studio, workshop and guest house. It is also designed so that it may function as a rental home if needed. Our initial round of planning looked at how the spaces might work as a rental thinking that those functional requirements would be more restrictive than the requirements for an art studio and workshop.

Elements common to all three schematic design options:

All three options place the cottage at the SW corner of the site, chosen for it's relationship to the more public areas of the existing home and for an opportunity to create a shared outdoor room for both the cottage and the home. They all have a gable roof which was chosen for the height bonus allowed in the ordnance and to help marry the form of the cottage to the form of the existing home. All three options have the kitchen, living and bath rooms on the first floor and a bedroom loft on the second floor. Another feature common to all the options is the use of salvaged galvanized steel scaffolding components (see image below) which we plan to use as treads for ladder to the loft spaces.



This design incorporates an existing garage which more or less sits on the South and West property lines. The city land use desk (walk in) indicated that it was probable that we would be able to grandfather the building envelope of the existing garage into a new backyard cottage but they were unwilling to guarantee it. They recommended that we go through formal land use approval early in the process. Regardless of their final call we did know that we would have to stick within the building envelope of the garage for all portions of the backyard cottage that did not conform to the new ordinance. The potential advantage of using the existing garage is that it would allow us to use up less of the yard space for our new structure.


This drawing illustrates the site plan and floor plans. The existing garage is the portion of the structure that bumps out to the south and the west.


This is a view of the cottage from the SE. You can see the envelope of the existing garage on the south side of the structure.


A view from the NE looking through the shared outdoor room.


A view looking from the dining room, past the scaffolding ladder and into the living area.


A view from the living room into a private shade garden inspired by small Japanese courtyard gardens and created in the 5' setback from the lot line. a four foot concrete wall and cedar fence above create a very private and intimate indoor/outdoor space.


A view from the street.


The major element in this design is the creation of a covered outdoor workspace to the south of the cottage.


The covered patio to the south provides a sheltered outdoor workspace. The loft space is pulled back from the east wall allowing two stories of light to fill the first floor studio.

option2-courtyard-from-SView from the SE


View from the NE


Loft space


This scheme ended up being the winner with Kate and Ric. They felt it was the best fit for their needs in terms of layout and size. It features a simple open plan on the first floor and a second floor that is more private than the lofts in the first two options.


Pass through doors and a simple plan define this scheme.


View from the SE.


View from the NE.


Entry from shared outdoor room


Looking toward the kitchen and dining room.


Bath with a private shade garden.



Seattle Backyard cottages - The the dpd posts a new cam

CAM-116B The Department of Planning and Development (DPD) has posted a new client assistance memo (CAM) to outline the citywide backyard cottage ordinance. CAMs are guides intended to help people navigate the building permit processes in the city of Seattle.

CAM 116B, Establishing a Backyard Cottage (Detached Accessory Dwelling Unit) "This Client Assistance Memo (CAM) explains the requirements and process for establishing a detached accessory dwelling unit (also called a DADU or mother-in-law unit) on an owner-occupied Single Family zoned lot in southeast Seattle."

If you are considering building a cottage in your backyard it is still worth reviewing the DPD's older, more comprehensive (but now somewhat inaccurate) publication: "A Guide to Building a Backyard Cottage in Southeast Seattle."

BLOGGING A SEATTLE BACKYARD COTTAGE - a CAST architecture case study project

house Greenwood resident Kate Lichtenstein contacted us last spring to help her design a backyard studio / guest house for her modest 650 square foot 1920's one bedroom home (shown above). While the home's scale fits nicely with Kate's desire to have a simple and ecologically responsible lifestyle it falls a little short when it comes to a rough and ready workshop space for art, bicycle repair, ski tuning and building projects. Kate's home also lacks the space for a home office / guest room - something that she would like to integrate into the new structure.

Our initial goal was to have her project under construction by late summer 2009 but we were unable to get the project off the ground by that time. In hindsight, the stalling of the project turned out to be a stroke of luck...

In March of 2009 Seattle Mayor Greg Nickels proposed legislation that would allow Seattle homeowners to construct backyard cottages on their property. The legislation was reviewed and ultimately passed by the Seattle city council on November 2nd 2009 (with a 9 to 0 vote too! Kudos to Seattle voters for electing progressive urbanists for city council members!).

For Kate the ordinance has opened up new possibilities for a structure that can both accommodate her current needs and provide a potential source of income as a rental unit if her finances ever fall on hard times. Besides allowing for a legal detached rental unit the ordinance also allows for the construction of a two story structure – an arrangement that will work well for Kate’s needs and will help to preserve the spaciousness of her backyard.

Kate is planning to build with a mind toward sustainability and has a special interest in using recycled building materials whenever possible (she is, at this time, planning to write a parallel blog on the topic of recycled building materials). For us at CAST architecture Kate's project is an exciting chance to test out the new backyard cottage ordinance and work with a client who is committed to building green. We see her project as an excellent opportunity to provide the general public with information about the process of designing and building a backyard cottage in Seattle. Kate and her partner Ric Cochrane are always game for an adventure and have graciously agreed to allow us to share their experience with you. To that end, we are planning to blog about Kate's project as we travel through the design and construction process. Please subscribe to our feed if you would like to follow along in future posts…


Breaking---Backyard cottages pass 9-0!

The ordinance  to allow backyard cottages in the other three quarters of Seattle just passed 9-0!  The council's comments focused on the exhaustive community outreach, successful pilot program and benefit of having this housing choice for Seattle. Excellent work by the planning commission, DPD and council.

Usually, the city's process oriented decision making can be cumbersome, and having spent hours in meetings, testifying, and communicating with council, I feel vindicated that our involvement has helped in some small way to bring some innovation to the Single Family zoning.

We're excited to design some of these--in part because of the opportunity to foster multi-generational housing, and the option of building a smaller free standing structure rather than building an addition.  Plus, it is a really fun scale--I think more people will be thinking about bonus studios rather than housing units.

My backyard cottage idea: what would you do?

northwest perspective showing clerestory band wrapping studio and office north elevation: office over guest suite to the left/studio to the right

With the impending vote on the backyard cottage ordinance, everyone in the office has been doing a little daydreaming about the DADUs and what they would build.  I have been working on a idea that started with a little ink drawing. It's now developed into a preliminary model/floor plans.  I've flipped the shed roof to have more volume in the shop/studio and worked out the bathroom so that my shop could easily be converted into an open kitchen/living space.

I have also been working out a simple steel structure, clad with structural insulated panels for easy construction and minimization of waste.  The goal is prefabrication of the components offsite, then assemble.

I'd love to try out using a geothermal pre-heating loop, with a hydronic radiant system run of a domestic hot water heater and test the new PV shingles, but that might get a bit expensive.

Seattle Backyard Cottages-Land Use meeting recap

We're almost there--the committee passed the measure to allow backyard cottages in Seattle.  Next stop will be City Council. There are some notable amendments to the ordinance--the 50 per year allowed cap has been eliminated.  The heights have changed somewhat.  A discussion to limit the cottage height to no more than 15' above the primary residence's roof (which would affect sloped lots primarily) was tabled without conclusion.

The discussion is a little strange, in that some of the requirements being tossed around are more stringent than for building a single family house.  Case in point--if this relative height limit section passes, you will need a topographic survey to prove that the cottage conforms (not required on a new house if well within setbacks and under height), thus added about $2000 to the pricetag for the drawings.  This doesn't make any sense if the city is serious about this as being an affortable option.

Another case in point--Councilmember Rasmussen was leaning toward a neighborhood notice, similar to a MUP, but the neighbor's recourse, provided the cottage design fits the requirements, is nil.  The cottage is a Level 1 decision (no notice necessary, just like a new single family house), but creating such a provision would form a special class of notice ("Here is what is happening next door, but there is nothing you can do about it.  Thanks for coming down.").

Unfortunately, I had to run out before the discussion on the privacy issue, another NIMBY favorite, but in the end the ordinance is one step closer to fruition.

You can see the entire meeting online at the Seattle Channel here.  Backyard Cottage discussion starts at 107.30.


The Planning, Land-Use and Neighborhood Committee is planning on voting on the Backyard Cottages on October 8th.  Last chance to make yourself heard on this issue! It will be a packed agenda, with discussions of the Multi-family code revision as well as the design review process (which will be mandatory in Multi-family).

Multifamily code update

L3-max-front-NE-2 In the last month, the City Council paid 3 groups to study the new MF code and flesh out some likely outcomes (good and bad) and propose revisions to the code.  It is a complex issue--the code revision itself is about 277 pages--and no doubt the Council were daunted by the prospect of interpreting the impact.  It took me two evenings just to get through the entire code and I am still not sure I've got a handle on all the ins and outs.

The three groups were the Masterbuilders Association, the Congress of Residential Architects, and Group Three (composed of unaffiliated concerned citizens).  Each group were paid 5k for their work (our fee went to CORA--not to the  8 individual participants).  Here are my impressions from the three groups:


The MBA group, lead by Arg Consulting and Pb Elemental focused on fee simple townhomes, 1200 sf-1600sf each, on both the L1 and L3 sites.  One gable style, one flat roof style option for each site given in the program.  The schemes prioritized surface parking (I think one scheme had garages).  The site designs either a central surface parking lot, accessed along a longitudinal drive or perpendicular parking off an alley.  The reduction in setbacks meant the building volumes were spread to the site edges.  These would be cheap to build--fee simple boxes, surface parking, no cantilevers--and  therefore probably the most likely to get built under the new code.  Which is depressing, when you extrapolate it to the scale of the city.

The other remarkable thing is that the MBA group left development capacity on the table in order to have straight forward rectangles.  The most dense scheme had 6 units (on 7200 sf= 1200 sf per unit) well below the 800 sf per unit allowable now.  It seems hard to believe that developers best use of the lot is solely dictated by construction simplicity.  My back of the envelop calculation would put the FAR between 1 and 1.34 (6 units X 1200 or 1600 sf per = between 7200 sf and 9600sf divided by 7200 sf lot), less than the 1.4 allowed.  The outcome of the MBA exploration is big units, minimal density, and pushed to the property lines so there is enough space to have cheap surface parking. That isn't to say that all the other groups' schemes made economic sense, but if this is their best option, the proposed mandatory design review has to have some more bite, because we'll definitely be seeing these bland site plans again all over town.


The second presenter, the Congress of Residential Architects, had a lot of diversity in both type, density, good and bad.  CORA explored ground related townhouses, high density apartments, even row houses. We tried to find the limits, loopholes and boy did we create some code compliant cringe-worthy options, as well as some good options that would require departures.  David Neiman and Bradley Khouri deserve praise for herding the cats.   Here is a little conclusion that David Neiman wrote:

"There are certainly some problems with loopholes & some flawed gating mechanisms that we identified.  The bad news is that our bad schemes are even worse than what you can do today.  The good news, however, is that the culprits aren't very hard to find, and they aren't hard to fix.  Overall, we remain strong supporters of the Multi-Family Update.  It just needs some work under the hood.

Code changes recommended to make bad schemes better:

1.  Above 1.1 FAR, the wheels start to come off the cart for most ground based housing schemes.  At 1.4 FAR most ground based housing schemes are a disaster.  We need to revisit allowable FAR & use it as a tool to reward desirable features & outcomes.  For small-lot ground-based housing, FAR needs to be kept relatively low.  For structured parking solutions, large lots, and projects that undergo full design review, higher FAR is appropriate.  See executive summary.

2.   The residential amenities requirement is far too permissive – it reduces open space to an afterthought.  It's not hard to correct.  The requirements just need to be dialed up to be more significant.  See executive summary for proposal.

Code changes recommended to make good outcomes into better outcomes:

1.    Lift the density limits to allow diverse unit types, sizes, affordability levels.

2.    Return to a 30' base height limit for all L-zones w/ a 4' height bonus in L3 for structured parking.

3.    Encourage basements by exempting them from FAR – you get a privacy grade break & create opportunities for inexpensive rental flats.

4.   Green factor.  If it were working, it would incentivize open space, privacy screening, tree planting & permeability.  It does none of those things; it simply covers your land in shrubs & your walls in vines.

5.   See executive summary for more."

There will be more information and a pdf of our work forthcoming.

Group Three:

Because this post is getting long, I am going to rapidly summarize the Group 3:  Lots of double lot schemes, and generally trying to put a bad face on each.  I am not sure if anything they put up there would be something they'd like to see built.  There was a preposterous presentation of anecdotal evidence that when houses are closer than15' to the sidewalk that window blinds are always closed, and it emotes an unsafe neighborhood, therefore the front yard setbacks must be 15' feet.  One merely has to walk around any neighborhood to see front blinds drawn--it is not a function of distance to sidewalk.  There was a recurring complaint that street trees weren't provided or required and that more of the green factor elements would die or get removed (I envisioned a truck with mobile planters with trees being carted from one property to another to fulfill Green Factor, get the final inspection, then on to the next development).  I actually agree with this--by setting the level of Green Factor too high, they will be pushing unsustainable planting (one of their schemes had a vegetable garden at the bottom of a four story light well).   And they ground the axe of allowing developers to subdivide properties to take advantage of the rounding up allowed by unit density rules.  The presentation was a pretty cynical take on the new code.

If you have questions, or comments, I'd love to hear about them!

Seattle Multi Family Code update: news from yesterday's meeting

CAST has been involved in reworking the Multi-family code for the City of Seattle--this byzantine, arcane legacy that seems to produce the dreaded Four Pack/Six Pack around a shared auto court. The proposed code is evolutionary, and at this point, has been watered to down to the point that the impact will not affect the majority of lowrise multifamily that goes up in Seattle.  It is pretty disappointing in general, but a couple of highlights:

1. The move to FAR rather than density limits for number of unit will create more demand for smaller units in the L3 zone

2.  The setbacks are reduced--good for the urban sidewalk edge, and allow raised stoops in the front yard.

3. Height bonuses for workforce housing, and green building are going to get used--an example of incentivizing good construction.

And a couple of lowlights:

1.  Green Factor's heart in is the right place, but the high baseline is going to force some heavy gaming of the rules, such as fences become 'vegetated walls', and green roofs are going to go in then be abandoned.  The city would be better off lowering the baseline and focusing it on green factors that are going to be maintained and become beneficial for the environment and the city.

2.  Density limits in L1 remain, and thus there is zero impetus to alter the 4 pack in any meaningful way.

3.  Partially below grade parking doesn't count toward FAR (that's good), but doesn't give you additional height--meaning no one is going to pay to bury the parking if they are then also not able to offset the cost with a third story of marketable square footage.

I'll post more info later....